Tire tread patterns are available in a wide variety of designs and appearances and may include both aesthetic and functional features depending upon the intended application. Certain tread features may improve traction, braking, and performance in inclement weather conditions such as rain, snow, or ice. These and still other tread features may also provide ornamental aspects intended to be visually attractive to the buyer.
Various complexities are encountered in the process of converting a selected pattern or design into an actual tire tread that can be manufactured repeatedly. Ultimately, a mold must be created that will repeatedly duplicate the pattern on either the tread region of a tire or a tread belt in the case of retreading operations. For example, a mold may be constructed from a metal such as e.g., aluminum that has in turn been cast or injected from an intermediate mold—referred to as a mold negative—constructed from yet another material such as e.g., plaster or a machined metal part.
The creation and transfer of the desired pattern from drawings to mold negative to the final mold component is particularly problematic with certain types of tread features. For example, many tread features have a three-dimensional aspect i.e., changes in the rubber surface occurring in the radial directions (R) as well as in the axial and circumferential directions (C) of the tire. Multiple variations in three-dimensions are difficult to construct into a mold that will repeatedly duplicate the desired pattern into rubber, especially when an undercut in the radial direction of the tire is desired.
In addition, small grooves or slits—sometimes referred to as sipes—are frequently added to a tire tread to increase traction and/or provide certain visual effects. For certain applications, it may be desirable to have sipes forming a particular pattern and/or enclosing a particular rubber shape. For example, a circular sipe surrounding a rubber portion that in turn is recessed, flush, or protruding can provide certain tire performance advantages. However, construction of such tread features is difficult to provide with the conventional tire mold or molding process.
Accordingly, a device and method for manufacturing features into the tread pattern of a tire that addresses the difficulties identified above as well as other challenges would be useful and advantageous. A device and method that allows for the manufacture of various tread patterns having features that may be raised, recessed, or flush with the surrounding tread surface would also be particularly useful and advantageous.